But most of them don't know if big data is worth it—yet. And they're not even sure what it means, with the "big data" label applied to all kinds of data-intensive projects.

Most companies said that "big data" meant scooping up large quantities of information, often from nontraditional, server-busting sources like Web traffic logs or social media, and then using it to make business decisions in real time. These include things like watching competitors, monitoring their own brands, creating new services that they can sell, and tracking product and pricing information.

In 2012, companies worldwide spent $4.3 billion on software for big-data projects, market research firm Gartner reports. Most of that was for software running on company-owned servers.

But in a survey of over 800 business and IT professionals commissioned by big-data startup Connotate, 60% said it was too early to tell if a given project was successful and returned a decent value for its investment.

That won't stop companies from spending even more on big-data projects next year. They'll be buying new servers and software and hiring experts. Add it up, and big-data projects will drive $34 billion of technology spending in 2013, Gartner predicts.